WACC Calculator
Calculate the Weighted Average Cost of Capital — the discount rate that blends the cost of equity (via CAPM) and after-tax cost of debt, weighted by capital structure.
Rows = Beta, Columns = ERP
How to Use This WACC Calculator
WACC has two halves — the cost of equity and the cost of debt — blended by how much of each a company uses to finance itself. Start on the equity side: plug in the current risk-free rate (the 10-year US Treasury yield, which you can find on any financial site), the stock’s beta (a measure of volatility relative to the market — available on Yahoo Finance, Bloomberg, or your brokerage), and the equity risk premium (the extra return investors demand over the risk-free rate, historically around 5–6%).
For the debt side, enter the company’s pre-tax cost of debt — the simplest estimate is interest expense divided by total debt, or the yield on the company’s outstanding bonds. The corporate tax rate defaults to 21% (US federal). Finally, enter the market value of equity (market cap) and the market value of debt (book value is an acceptable proxy) to set the capital structure weights.
The result is the blended rate you’d use as the discount rate in a DCF valuation or any present value analysis.
The WACC Formula
Ke = Cost of equity, Kd = Pre-tax cost of debt, T = Tax rate
WACC is the minimum return a company must earn on its existing assets to satisfy both its shareholders and its lenders. It’s the “hurdle rate” — if a project or acquisition can’t clear the WACC, it destroys value. For investors, WACC is the discount rate used in a discounted cash flow model to convert future free cash flows into present value.
The tax shield on debt (the (1 − T) term) is what makes debt cheaper than equity on an after-tax basis. Interest payments are tax-deductible, so the government effectively subsidizes part of the cost. That’s why adding some debt can actually lower WACC — up to a point.
Cost of Equity: CAPM Explained
The Capital Asset Pricing Model (CAPM) is the standard framework for estimating the cost of equity. It says: the return investors demand equals the risk-free rate plus a premium for bearing market risk, scaled by the stock’s beta.
| Component | What It Represents | Typical Value | Where to Find It |
|---|---|---|---|
| Risk-Free Rate (Rf) | Return on a “riskless” asset | 3.5–5% (varies with rates) | 10-yr US Treasury yield |
| Beta (β) | Stock’s sensitivity to market moves | 0.5 (defensive) – 2.0 (volatile) | Yahoo Finance, Bloomberg |
| Equity Risk Premium (ERP) | Extra return for stock vs bonds | 5.0–6.5% | Damodaran’s annual estimate |
| Size Premium | Extra return for small-cap risk | 0–3% | Duff & Phelps / Kroll data |
A stock with a beta of 1.5 has been 50% more volatile than the market — so CAPM says investors need 50% more risk premium to hold it. A stock with beta 0.7 is less volatile, so its cost of equity is lower. Beta measures systematic (market) risk, not total risk.
Betas are backward-looking, noisy, and vary depending on the time period and index you measure against. A 2-year weekly beta vs the S&P 500 will differ from a 5-year monthly beta. For WACC purposes, use the industry average (unlevered) beta and re-lever it for the company’s capital structure — this gives a more stable estimate than the raw regression beta.
Cost of Debt and the Tax Shield
The cost of debt is simpler: it’s the interest rate the company pays on its borrowings. You can estimate it as interest expense divided by total debt, or look at the yield-to-maturity on the company’s outstanding bonds.
Because interest is tax-deductible, the after-tax cost is lower than the nominal rate: After-Tax Kd = Kd × (1 − Tax Rate). At a 21% US corporate tax rate, a 6% borrowing rate costs the company only 4.74% after the tax shield.
| Credit Rating | Typical Spread Over Treasuries | Pre-Tax Cost (approx) | After-Tax Cost (21% rate) |
|---|---|---|---|
| AAA | +0.5–0.8% | 4.8–5.1% | 3.8–4.0% |
| A | +1.0–1.5% | 5.3–5.8% | 4.2–4.6% |
| BBB | +1.5–2.5% | 5.8–6.8% | 4.6–5.4% |
| BB (High Yield) | +3.0–5.0% | 7.3–9.3% | 5.8–7.3% |
| B / CCC | +5.0–10.0% | 9.3–14.3% | 7.3–11.3% |
Capital Structure: The Optimal Mix
Because debt is cheaper than equity (due to the tax shield and priority in liquidation), adding leverage initially lowers WACC. But past a certain point, the rising risk of financial distress — potential bankruptcy, loss of customers, restricted operations — pushes both the cost of debt and cost of equity up, and WACC starts climbing again. The theoretical minimum is the “optimal capital structure.”
| Sector | Typical Debt/Capital | Why |
|---|---|---|
| Technology | 5–15% | Asset-light, volatile earnings — limited debt capacity |
| Healthcare / Pharma | 15–25% | Moderate; patents create some stable cash flow |
| Industrials | 25–40% | Tangible assets for collateral, cyclical but established |
| Utilities | 40–60% | Regulated, predictable cash flows support heavy leverage |
| REITs | 30–50% | Real assets as collateral, stable rental income |
The Leverage Curve tab on this calculator visualizes how WACC changes as you shift the debt-to-capital ratio — you can see the U-shaped relationship that corporate finance textbooks describe.
WACC weights should use market values of equity and debt, not book values. Equity market value = share price × shares outstanding (market cap). For debt, book value is an acceptable proxy if bonds aren’t publicly traded, but if they are, use the market price. Using book equity for a high-growth tech company will dramatically overweight debt and understate WACC.
Related Tools
| Calculator | Use It For |
|---|---|
| DCF Calculator | Plug your WACC into a full discounted cash flow valuation |
| Present Value Calculator | Discount any single future cash flow at your WACC |
| ROI Calculator | Compare actual investment return to your cost of capital |
| Compound Interest Calculator | General compounding at any rate |
| Future Value Calculator | Project a lump sum forward at a given WACC |
| Rule of 72 Calculator | Quick doubling-time estimate at any cost of capital |
FAQ
What is WACC and why does it matter?
WACC (Weighted Average Cost of Capital) is the blended rate of return a company must earn to satisfy both equity investors and debt holders. It’s the discount rate used in DCF analysis, the hurdle rate for capital budgeting decisions, and the benchmark for evaluating whether a company is creating or destroying value. If a project’s return exceeds WACC, it creates shareholder value; if it falls below, it destroys it.
What risk-free rate should I use?
Use the 10-year US Treasury yield for US-focused analysis. It matches the duration of most DCF forecasts (10 years) and is considered the closest thing to a truly riskless investment. As of recent years, this has ranged from about 3.5% to 5% depending on the rate environment. For non-US companies, use the corresponding sovereign bond in the company’s home currency.
Where do I find a company’s beta?
Most financial data providers (Yahoo Finance, Bloomberg, Morningstar) report regression betas. However, raw betas are noisy and backward-looking. For a more stable WACC, use the industry average unlevered beta from Professor Damodaran’s dataset (publicly available), then re-lever it for your target company’s capital structure. This smooths out company-specific volatility that doesn’t reflect true systematic risk.
What equity risk premium should I use?
The historical US ERP is approximately 5–6% (stock returns minus the risk-free rate over long periods). Professor Aswath Damodaran publishes an annual implied ERP estimate based on current market prices, which fluctuates between 4–7%. For most US-focused DCF valuations, 5.0–6.0% is a reasonable range. Use a higher ERP for emerging markets.
How do I estimate the cost of debt?
The cleanest approach: interest expense ÷ total debt. Alternatively, find the yield-to-maturity on the company’s outstanding bonds. If the company doesn’t have public bonds, use the credit rating to estimate a spread over Treasuries (see the table above). For private companies, look at the interest rates on their bank loans or lines of credit.
Should I use market or book values for weights?
Market values, always. The cost of equity compensates investors at the market price they paid, not the accounting value. For equity, market value = share price × shares outstanding. For debt, book value is an acceptable proxy since most debt trades near par, but use market value if the bonds are publicly traded and trading at a significant premium or discount.
Why is debt cheaper than equity?
Two reasons. First, the tax shield: interest payments are tax-deductible, reducing the effective cost by the tax rate. Second, debt holders have priority over equity holders in bankruptcy — less risk means lower required return. But this cost advantage disappears if you lever up too much, because the risk of financial distress raises both the cost of debt and equity.
How sensitive is WACC to its inputs?
Very. A 1% change in the equity risk premium or a 0.2 change in beta can shift WACC by 50–100+ basis points, which meaningfully changes a DCF valuation. That’s why the sensitivity table on this calculator is essential — it shows how WACC moves across a range of betas and ERPs so you can see the full range of reasonable estimates, not just one point.
Key Takeaways
- WACC is the discount rate for DCF — it blends the cost of equity (CAPM) and after-tax cost of debt, weighted by capital structure.
- The cost of equity is always higher than the cost of debt — equity holders bear more risk (residual claim, no guaranteed payments) and demand a higher return.
- The tax shield makes debt cheaper — at a 21% corporate rate, a 6% borrowing cost becomes 4.74% after tax. This is why some leverage lowers WACC.
- Use market values for weights — book values can be wildly different, especially for high-growth companies where market cap far exceeds book equity.
- Beta is noisy — prefer industry-average unlevered betas re-levered for the target’s capital structure over raw regression betas.
- Always run a sensitivity analysis — a single WACC is a false precision. Show the range and let the analysis drive the conclusion, not a single decimal.